BUG: set keyword argument so zipfile actually compresses by minggli · Pull Request #21144 · pandas-dev/pandas (original) (raw)

• closes DataFrame.to_pickle() fails for .zip format on MacOS and pandas 0.20.3 #17778
• tests added / passed
• passes git diff upstream/master -u -- "*.py" | flake8 --diff
• whatsnew entry

zipfile.ZipFile has default compression mode zipfile.ZIP_STORED. It creates an uncompressed archive member. Whilst it doesn't cause issue, it is a strange default to have given users would want to compress files.

In order for zip compression to actually reduce file size, keyword argument compression=zipfile.ZIP_DEFLATED is added.